1. Technical Field
The invention relates to dispensing liners and protective seals for jars and other containers, and to methods for making such dispensing liners and protective seals.
2. Background Art
Containers with shaker tops are useful for storing and dispensing powders, flakes, and other particulate contents, such as spices and seasonings. A typical shaker top includes a dispensing liner that extends across the open mouth of a container such as a wide-necked jar. The dispensing liner contains at least one perforation, which is of a size that permits the controlled release of contents from the container, by actions such as shaking and sifting. To prevent spoilage and loss of contents during shipping and storage, the dispensing liner is usually sealed with a peelable protective cover, also known as a “freshness seal”, which occludes the perforations of the dispensing liner. The protective cover is affixed to the dispensing liner with an adhesive weak enough to permit its removal by a user, prior to dispensing the contents from the container.
A typical shaker top is disclosed by U.S. Pat. No. 5,513,781, to Ullrich, et al. (“Ullrich”). The shaker top includes a dispensing liner in the form of a perforated sifter. The sifter extends across the mouth of a bottle. A protective cover, in the form of a peel-away liner, is sealed over the top surface of the sifter, to cover at least the perforations of the sifter. The sifter preferably includes a metallic foil such as aluminum foil, because such foils can be induction sealed to the mouth of the bottle. In induction sealing, an adhesive layer, such as a heat sealable polymer film, is laminated to a metal foil. The laminate is then exposed to an induction coil emitting an oscillating electromagnetic field. Induced current in the foil melts the polymer film, which flows into the gap between the foil and a substrate, such as the mouth of a bottle. When cooled, the polymer film forms an adhesive bond between the foil and the substrate. In the shaker top of Ullrich, both the sifter and the peel-away liner include heat sealable adhesive layers. A closure cap, such as a threaded screw-on cap, protects the entire shaker top assembly.
A container top disclosed by U.S. Patent Application Publication No. 2003/0168423, to Williams, is designed for dispensing of liquids. It includes an induction sealed barrier film with a pour spout, rather than a sifter top, but is otherwise similar to the shaker top disclosed by Ullrich.
Ullrich also discloses a typical method for manufacturing a bottle having a shaker top. The sifter, peel-away liner, and their adhesive layers, are assembled into a package, which is mounted within a specialized retaining area within the closure cap. The mounting of the package in the retaining area is mediated by a friction fit, or by an adhesive. The package and closure cap are stored or transported as a unit, with the elements of the package being held in alignment by confinement within the retaining area of the closure cap. The package and closure cap are then mounted upon the neck of a bottle or other container, and subjected to induction bonding. The sifter is sealed across the neck of the bottle, and the peel-away liner is sealed to the sifter, beneath the closure cap.
The method of Ullrich is efficient, but it imposes restrictions upon the sizes and compositions of the sifter and protective liner, and upon the structure of the closure cap. For example, a protective liner that is smaller in diameter than the sifter may be desirable, but cannot be used with the Ullrich method. A protective liner smaller than the diameter of the sifter will not be securely confined within a closure cap whose retaining area accommodates the wider sifter. The protective liner is therefore likely to slip out of alignment with the perforations in the sifter during shipping and handling of the package-closure cap unit. The choice of closure caps is also restricted. Well known, off-the-shelf closure caps cannot be used with the Ullrich method, for they lack a retaining area to keep the package in proper alignment.
There is a need for a method for manufacturing shaker tops without preassembling components into a package prior to mounting upon a container. There is also a need for the diverse assortment of shaker tops that can be produced by such a method of manufacture.